Expansion of compressed cork particles by steaming



sure liners, textile cots, and the like.

UNITED STATES PATENT OFFICE EXPANSION F COMPRESSED CORK PARTICLES BY STEAMING Carl J. Schallcr, Lancaster, Pa., assignor to Armstrong Cork Company, Lancaster, Pa., a corporation of Pennsylvania No Drawing. Application June 28, 1947, Serial No. 757,955

9 Claims. (01. 252-378) This invention relates to the expansion of compressed cork particles. More particularly, the

invention relates to a method of expanding cork particles which may be employed in the marin facture of formed articles from cork composition.

Cork composition is Widely employed in the manufacture of material for use as gaskets, clo- The par ticular articles are generally molded, extruded, or otherwise shaped from cork compositions com prising cork particles and a suitable binder, such as glue, glue-glycerine, rubber latex, or other binding material.

Generally speaking, cork particles and binder are mixed and then molded by suitable means at elevated temperature to produce the cured cork composition having a desired shape which may be further shaped by cutting or other means to obtain the particular article desired.

Ordinarily, cork composition is prepared from cork particles ranging in size from 5 to mesh to to 50 mesh, the particular size employed depending upon the desired nature of the final product. The cork particles employed are generally obtained by grinding or otherwise disintegrating natural cork, or they may be recovered from other manufacturing processes employing cork particles. Generally speaking, the particles are shipped in bags, and, because of the nature of the material, a substantial amount of shipping space is required for a given weight of cork. In certain instances wherein grinding equipment is not available, the procedure has been attempted in which cork is granulated at a point where such equipment is available and then baled and shipped to the point where the material is to be formed into cork composition by mixing with binders and curing in the usual manner. However; attempts to make cork composition under such circumstances have proven unsuccessful as the products obtained from this compressed cork are unsuitable for use. Genrally speaking, in the baling operation, the cork particles, which are generally approximately spherical and/or cubical, depending, among other things, upon the type of grinding employed to obtain granulation, are subjected to sufiicient pressure, such as at least 150 pounds per square inch, to compress them into a mass of the desired volume. Due to the true compressibility of the cork, the particles are generally flattened in one direction. Since the baled cork is maintained under compression for extended periods, such as at least two weeks, the particles develop a permanent set. When attempts are made to manufacture composition from the compressed particles, the binder covers only the top and bottom surfaces of the flattened pieces, and, during the baking operation, the particles tend somewhat to expand, exposing fresh surfaces without binder. In addition, because of the flat nature of the particles, a comparatively low amount of pressure is required to compact a given quantity of particles in a mold, and a poor bond between particles results. These factors, among others, result in a weak composition.

Various methods have been proposed for expanding compressed cork particles, and, although entirely satisfactory results have been obtained, these methods are generally of such a nature as to require two stages for their operation. The first stage is that involving the disintegration of the large mass of compressed cork which is generally carried out by some mechanical means. Following the mechanical disintegration, the compressed particles are then subjected to suitable treatment to expand them back to substantially their'original density. In addition, the actual expansion takes considerable time.

It is an object of this invention to provide a simple method of expanding cork particles with have been subjected to high pressures for the purpose of reducing their volume.

A further object of this invention is the provision of a method of expanding compressed cork particles which may be rapidly carried out in simple equipment.

Still another object of this invention is the provision of a method of expanding cork particles which results in the production of expanded particles having little difference in composition from the particles prior to compression.

Still another object of this invention is the provision of a method of expanding compressed cork particles which results in a material which can be utilized in the preparation of cork composition containing a wide variety of binding agents.

These and other objects of the invention will become apparent to those skilled in the art upon becoming familiar with the following description.

I have found that cork particles which have been compressed in order to reduce their volume to facilitate handling, shipment, storage, and the like may be rapidly expanded to substantially their original dimensions and density by exposing the particles to the action of exhaust steam for a short period of time.

.Example I. months, the cork particles had a density of 3.9

In accordance with my invention, cork particles which have been subjected to high pressures, for example, at least approximately 150 pounds per square inch, during baling operation are advantageously'subjected to a jet or other source of exhaust steam in a closed container. The entire mass of cork, for example, a bale of cork, may be placed in a suitable vessel having a source of supply of exhaust steam, and, after a short period of time of exposure to such steam, the bale is completely disintegrated, and the individual particles have been expanded to substantially their original dimensions with a resulting decrease in density which yields a final product having a density substantially equal to the density of the material before compression.

While the time required for expansion may vary, depending, among other things, upon the particle size of the cork, the type of equipment in which the expansion is being efiected, the size of the agglomerate of compressed particles, and the like, generally speaking, exposure of the particles for such a short period of time as about 15 to 30 seconds results in changing the density of the compressed cork to such an extent that it is equal to approximately the density of the cork prior to compressure.

My invention may be more readily understood by reference to the following specific examples.

Example I A quantity of 5 to mesh cork particles hav-- ing a density of 2.9 pounds per cubic foot was placed under 1500 pounds per square inch ram pressure which was equivalent to 150 pounds per square inch on the cork.

The cork was held at this pressure for 5 to 10 minutes. After baling in this manner and storage for 18 months, the density of the cork particles was 4.5 pounds per cubic foot. A portion of the compressed cork in the form of loose granules was placed on a screen of about 20 meshes to the inch. The screen was placed on a steam bath, and a cover rag was placed on top of the screen to hold in the heat and moisture. Exhaust steam was then passed through the cork particles for seconds. The cork was visibly expanded after this procedure, and measurement of the density of the treated cork showed the density to be 2.9 pounds per cubic foot, which was equal to the density of the cork prior to the baling operation.

Example II A quantity of 10 to 20 mesh cork particles having a density of 2.8 pounds per cubic foot was baled under the identical conditions set forth in Example I. After baling and storage for 18 months, the cork particles had a density of 4.0 pounds per cubic foot. Using the same equipment as employed in the practice of Example I, exhaust steam was passed through the cork particles for 30 seconds. At the end of this period of time, the cork had a density of 2.8 pounds per cubic foot which was equal to the density prior to baling.

Example III A quantity of 20 to 40 mesh cork particles having a density of 2.5 pounds per cubic foot was baled in accordance with the method given in After baling and storage for .18

pounds per cubic foot. The cork particles were subjected to the action of exhaust steam for 30 4- seconds in the same manner andfor the same time as in Example I, and the resulting expanded cork particles had a density of 2.6 pounds per cubic foot which was substantially equal to the density of the cork particles prior to compression.

Generally speaking, during treatment in accordance with my invention, the cork picks up at most about 2% water which is practically negligible.

In a preferred embodiment of my invention, a bale of cork may be treated with exhaust steam, thus overcoming the necessity of mechanically disintegrating the compressed cork prior to treatment. Generally speaking, it is advantageous to conduct the operation in a closed or covered container. However, if desired, the expansion may be carried out in a container which is exposed to the atmosphere. In all cases, complete disintegration of the bale or other agglomerate of cork particles takes place very rapidly. Each particle is separated from the other, and no small lumps or balls or other similar masses of particles are left to be broken mechanically, even in the finest size cork.

The practice of my invention is extremely advantageous in those instances wherein it is desirable to compress particles for the resulting saving in shipping and/or storage space. By means of my invention, it is possible to compress granulated cork under such pressures that the material will occupy only about 10% to 20% of the space occupied by uncompressed material. Thus, there results considerable saving in storage space and also considerable reduction in the space required for shipment. Such a saving in space is of high importance as it enables a plant having comparatively limited storage facilities to build up a considerable supply of raw material for processing. Because of the simplicity of the method, the baled or otherwise compressed cork particles may be readily disintegrated and expanded back to substantially the original density of the particles.

Although my invention is particularly suitable for use in connection with the manufacture of cork composition including cork particles and a hinder, the expansion technique herein described may be applied to compressed cork particles which, after expansion, may be utilized without binder as loose cork filling, for example, as insulation for refrigerators and the like.

While my invention has been particularly described with reference to exhaust steam as the expanding medium, superheated steam may be employed in the practice of my invention. However, exhaust steam is preferred as careful control is required with superheated steam to avoid scorching of the cork particles and/or distillation .of some of the constitutents of the cork.

In the specification and in the claims, I have employed the term ermanent set or its equivalent as indicative of that condition obtaining after cork particles have been under compression and which prevents relaxation of the particles under normal conditions after removal of the compressive forces. While the time required to obtain this condition may vary, generally speaking, cork particles which have been under compression for two days to two weeks obtain a permanent set.

In the specific examples, densities of the cork particles have been set forth. These densities were determined by the Armstrong Tin Can Method. In accordance with this method, a

container 3.25" in diameter and 4.594" deep, having a capacity of approximately 624.5 cc. or

/45.: part of a cubic foot is filled to overflowing with reference to certain specific examples, it

is to be understood that the invention is not limited thereby. Therefore, changes, omissions, substitutions, and/or additions may be made without departing from the spirit of the invention as defined in the appended claims.

Iclaim: 1. A method of expanding compressed cork particles having a permanent set and which are I normally from 5 to mesh to to mesh comprising exposing said particles to steam at;-

atmospheric pressure until said particles have obtained substantially the density obtaining therein prior to compression Without changing the chemical structure of said particles.

2. A method of expanding permanently set cork particles which are normally from 5 to 10 mesh to 20 to 50 mesh and which have been baled by the application of pressure comprising contacting exhause steam with a mass of said f particles to disintegrate said mass and reduce the density of the individual particles to substan- E...-

tially that obtaining therein prior to said baling operation without changing the chemical structure of said particles.

3. A method of expanding permanently set:- i

cork particles which are normally from 5 to 10--.i'.

mesh to 20 to 50 mesh and which have been compacted by the application of pressures of about to 200 pounds per square inch comprising bringing steam at atmospheric pressure into contact with said compacted mass of particles to disintegrate said mass and reduce the density of the individual particles to substantially that ob-v taining in said particles prior to the compacting thereof without changing the chemical structure of said particles. l 4. A method of expanding cork particles which are normally from 5 to 10 mesh to 20 to 50 mesh and which have been compressed by the application of high pressures to obtain a compacted mass of high density particles which are permanently set comprising contacting exhaust; steam with said compacted mass under conditions sufiiciently drastic to disintegrate said mass and reduce the density of the individual par ticles to substantially that obtaining therein prior, to the application of pressure to said particles without changing the chemical structure thereof.

5. A method of expanding permanently set cork particles which are normally from 5 to 10 mesh to 20 to 50 mesh and which have been sub}? jected to pressures of at least pounds per square inch in a baling operation which cont-i prises disposing said bale of cork particles in the path of a stream of exhaust steam for a short period of time sufiicient to disintegrate said bale Number and to reduce the density of the individual particles to substantially that obtaining prior to said baling operation and recovering said particles of reduced density containing no more than 2% by weight additional moisture and having substantially the same chemical structure as the original particles.

6. A method of disintegrating an agglomerate of permanently set compressed cork particles which are normally from 5 to 10 mesh to 20 to 50 mesh which comprises disposing said agglomerate in the path of a stream of exhaust steam and recovering a loose mass of cork particles of substantially the same chemical structure as the original particles and containing no more than 2% by weight additional moisture.

.7. A method of disintegrating a bale of cork particles which are permanently set and which are normally from 5 to 10 mesh to 20 to 50 mesh which comprises contacting said bale With steam at atmospheric pressure and recovering a loose mass of cork particles having substantially the same chemical structure as the original particles and containing no more than 2% by weight additional moisture.

8. A method of expanding cork particles which are normally from 5 to 10 mesh to 20 to .50 mesh and which have been compressed by the application of high pressures to obtain a compacted mass of high density particles which are permanently set comprising contacting exhaust steam with said compacted mass while in an enclosed space under conditions sulliciently drastic to disintegrate said mass and reduce the density of the individual particles to substantially that obtaining therein prior to the application of pres sure to said particles without changing the chem ical structure thereof.

9. A method of expanding permanently set cork particles which are normally from 5 to 10 mesh to 20 to 50 mesh and which have been subjected to pressures of at least 150 pounds per square inch in a baling operation which comprises disposing said bale of cork particles in the path of a stream of exhaust steam for a short period of time sufiicient to disintegrate said bale and to reduce the density of the individual particles to substantially that obtaining prior to said baling operation without changing the chemical structure of said particles.

CARL J. SCHALLER.

REFERENCES CITED UNITED STATES PATENTS Name Date 2,301,148 Schwarz Nov. 3, 1942 2,350,422 Schuh June 6, 1944 2,422,522 Beveridge et a1. June 17, 1947 FOREIGN PATENTS Number Country Date 376,505 Italy NOV. 16, 1939 OTHER REFERENCES 7 Cork Insulation by Thomas, Nickerson. 8: Collins Co., 1928, p. 19. (Copy in Scientific Lib.) 

1. A METHOD OF EXPANDING COMPRESSED CORK PARTICLES HAVING A PERMANENT SET AND WHICH ARE NORMALLY FORM 5 TO 10 MESH TO 20 TO 50 MESH COMPRISING EXPOSING SAID PARTICLES TO STEAM AT ATMOSPHERIC PRESSURE UNTIL SAID PARTICLES HAVE OBTAINED SUBSTANTIALLY THE DENSITY OBTAINING THEREIN PRIOR TO COMPRESSION WITHOUT CHANGING THE CHEMICAL STRUCTURE OF SAID PARTICLES. 